The present invention relates to a bandwidth allocation system of a virtual path in an asynchronous transfer mode.
A conventional asynchronous transfer mode (ATM) coding system has time variations in amount of coding information, and pieces of information are multiplexed to efficiently utilize network resources.
Cell losses probabilistically occur during waiting for statistical multiplexing in a network, and therefore quality of communications is degraded.
In an ATM network, a virtual path arranged in a repeating line of an ATM communication scheme is not related to call generation, and the transmission capacity of the virtual path is determined in network design. In addition, whether a call is permitted or not is determined such that the bandwidth of a call is calculated on the basis of a traffic report value from a user upon generation of the call and compared with the empty capacity of the virtual path.
The virtual path is defined as a direct link which logically determines a route and a bandwidth in an arbitrary ATM switching network in a physical transmission network.
To assure the quality of the permitted call, cells in number larger than the report value of the user are monitored not to enter into the network in accordance with a policy control function. Priority control of transfer processes is performed in accordance with the attributes of terminals and media characteristics of communication information. A currently connected call is detoured to a new virtual path, thereby performing quality control.
In this conventional ATM communication scheme, the transmission capacity of a plurality of virtual paths arranged in the ATM communication network is permanently determined, the bandwidth utilization for each virtual path is not constant, and the repeating line cannot be efficiently utilized.
When the transmission capacity of the virtual paths is set in consideration of a statistical multiplex effect and cells are output in number larger than a preset number, adverse influences of quality degradation such as cell losses are imposed on the entire repeating line.